 /*******************************************************************************
  * Copyright (c) 2000, 2006 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.core.internal.boot;

 import java.io.IOException ;
 import java.net.URL ;
 import org.eclipse.core.internal.runtime.CommonMessages;
 import org.eclipse.osgi.util.NLS;

 /**
  * Platform URL support
  * platform:/base/ maps to platform installation location
  */
 public class PlatformURLBaseConnection extends PlatformURLConnection {

     // platform/ protocol
 public static final String PLATFORM = "base"; //$NON-NLS-1$
 public static final String PLATFORM_URL_STRING = PlatformURLHandler.PROTOCOL + PlatformURLHandler.PROTOCOL_SEPARATOR + "/" + PLATFORM + "/"; //$NON-NLS-1$ //$NON-NLS-2$

     private static URL installURL;

     /*
      * Constructor for the class.
      */
     public PlatformURLBaseConnection(URL url) {
         super(url);
     }

     /* (non-Javadoc)
      * @see org.eclipse.equinox.internal.url.PlatformURLConnection#allowCaching()
      */
     protected boolean allowCaching() {
         return true;
     }

     /* (non-Javadoc)
      * @see org.eclipse.equinox.internal.url.PlatformURLConnection#resolve()
      */
     protected URL resolve() throws IOException {
         String spec = url.getFile().trim();
         if (spec.startsWith("/")) //$NON-NLS-1$
 spec = spec.substring(1);
         if (!spec.startsWith(PLATFORM + "/")) { //$NON-NLS-1$
 String message = NLS.bind(CommonMessages.url_badVariant, url);
             throw new IOException (message);
         }
         return spec.length() == PLATFORM.length() + 1 ? installURL : new URL (installURL, spec.substring(PLATFORM.length() + 1));
     }

     public static void startup(URL url) {
         // register connection type for platform:/base/ handling
 if (installURL != null)
             return;
         installURL = url;
         PlatformURLHandler.register(PLATFORM, PlatformURLBaseConnection.class);
     }
 }

